Control arm and counterbalance for overhead door



Nov. 29, 1955 D. M. ROBINSON CONTROL. ARM AND COUNTERBALANCE FOROVERHEAD DOOR Filed July 22, 1953 2 Sheets-Sheet 1 INVENTDR. DAV/D MPOB/NJ'ON ATTORNEYS CONTROL. ARM AND COUNTERBALANCE FOR OVERHEAD DOORFiled July 22, 1953 2 Sheets-Sheet 2 F/GJ F /G. 4 /0' AZ INVENTOR. DAV/D M POB/NSON A TORNEY5 United States Patent CONTROL ARM ANDCOUNTERBALANCE FOR OVERHEAD DOOR David M. Robinson, New Britain, Conn.,assignor to The Stanley Works, New Britain, Conn., a corporation ofConnecticut Application July 22, 1953, Serial No. 369,692

1 Claim. (Cl. 16-1) The present invention relates to swing-up doors andpertains, more particularly, to a counterbalancing mechanism forswing-up doors of the unarticulated type which are adapted to swingupwardly from a closed vertical position in the doorway to an openhorizontal position overhead.

In installations of doors of the type referred to, it is the usualpractice to provide counterbalancing mechanism to facilitate opening andclosing of the door. In some cases, the user prefers a counterbalancewhich will cause the door to open automatically whenever it isunlatched. In other cases, the user may prefer a counterbalance whichwill hold the door in closed position until it is manually startedtoward open position. It is therefore desirable to have a singlecounterbalancing mechanism which can meet either requirement and whichcan be adjusted for either type of operation in a simple and easymanner.

Accordingly it is an object of the invention to provide a counterbalancefor doors of the type referred to which is of economical and eflicientconstruction, which can be easily installed, which can be conditionedfor either automatic or non-automatic operation and wherein the meansfor selecting the type of operation desired is simple and easy tomanipulate and yet effective and foolproof in operation.

Other objects will be in part obvious, and in part pointed out more indetail hereinafter.

The invention accordingly consists in the features of construction,combination of elements and arrangement of parts which will beexemplified in the construction hereafter set forth and the scope of theapplication of which will be indicated in the appended claim.

In the accompanying drawings:

Fig. 1 is a fragmentary side elevational view of an overhead doorinstallation showing the counterbalancing mechanism of the presentinvention installed and adjusted for automatic operation;

Fig. 2 is an elevational View corresponding to Fig. 1, the view beingtaken in a direction looking at the rear of the door;

Fig. 3 is a view similar to Fig. 1 but with the counterbalancingmechanism adjusted for non-automatic operation of the door;

Fig. 4 is a sectional view taken in the direction of line 4-4 of Fig. l;and

Fig. 5 is an enlarged perspective view of the adjusting means with thecounterbalancing mechanism conditioned for automatic operation of thedoor.

Referring in detail to the drawings, there is depicted a doorway orframe bearing in general the reference numeral 10, the door framecomprising two spaced vertical side posts 12 and a bridging lintel orheader 14 connecting together the upper ends of the two side posts.Within the door frame 10 is a door 16, the rear face of which abutsagainst a pair of jamb strips 18 attached to the side posts 12 and ajamb strip 20 similarly fastened to the lintel 14.

2,724,857 Patented Nov. 29, 1955 Extending rear'wardly in a horizontaldirection from the upper ends of the pair of side posts 12 is a pair ofspaced horizontal tracks 22, the cross-sectional figuration of which isbest shown in Fig. 2. Within the confines of each track 22 is a roller24 mounted for rotation on a trolley 26, each trolley 26 being securedfast to the upper region of the door 16. For the purpose of supportingthe tracks 22, there is employed an end bracket 28 connecting theforward end of the track to one of the upstanding posts 12 and adjacentthe rear end of the track is a strap 30 afiixed to a portion of anoverhead beam constituting a part of the building structure itself.

Inasmuch as the upper end of the door 16 is-pivotally supported by thepair of trolleys 26, and the rollers 24 thereon may travel rearwardlyalong the tracks 22, the lower end of the door may be swung outwardlyand upwardly from its vertical closed position and into a horizontalopen position overhead. Co-operating to produce the path traversed bythe door in moving from a'closed to open position is a pair of swingingarms designated generally by the reference numeral 32, the lower ends ofthe arms being pivotally secured to the lower end of the door 16 bymeans of a pair of bearing brackets or ears 34 fastened in any suitablemanner such as by bolts or screws, to the door itself. Each of theswinging arms 32 is formed of angle iron 36 and has secured thereto atits upper end a bracket 38 having a flange 40 welded to the flange 42 ofthe arm.

Forming an integral part of each bracket 38 is a web 44 which serves tocarry a smaller flange 46 in a somewhat oifset manner from its otherflange 40. The flange 40 is provided with an anti-friction bearing 48 sothat the entire arm assemblage 32 may be pivotally mounted to a bracket50 which is in turn made fast to each post 12. In this way, the armassembly 32 pivots about the fixed point 48 as the door is moved from aclosed to open position.

Turning now to the counterbalancing mechanism generally indicated by thenumeral 52, it will be observed from the drawings that this mechanismincludes a pair of coil springs 54 adjustably anchored at their lowerends by a bracket or ear 56 secured to each of the vertical posts 12. Asuggested means of adjusting the tension in the coil spring 54 may takethe form of a rod or bolt 58 having a threaded end received in a platemember 60 engageable between any two adjacent convolutions near thelower end of the spring 54. By so connecting the lower end of thespring, it will be recognized that the tension of the spring may bevaried both by the particular convolutions selected for receivingtherebetween the plate 60, depending upon their proximity to the lowerend, and also, since the rod '58 is threaded, the advancing orretracting thereof with respect to the plate 60 and consequentlyrelative to the spring 54 itself. At the upper end of each spring 54 isdisposed a reversely bent strap 62 looped about a plate 64 placedbetween adjacent convolutions at this end of the spring. Accordingly,the particular convolutions selected for receiving the plate 64 maylikewise influence the degree of tension imposed upon the spring 54.

In accordance with the invention each of the straps 62 is connected tothe bracket 38 of the adjacent swinging arm 32 by means of a pair oflinks 66, the links 66 embracing the flange 46 and being pivotallyconnected thereto intermediate their ends by a pivot pin 68. The strap62 is inserted between the outer ends of the links 66 and is pivotallyconnected thereto by a pivot pin 70. The pivot pin 68 is located so thatthe center line between it and the bracket 56 when the door is closedfalls to the left of bearing 48 as viewed in Figs. 1 and 3 and the links66 are sufficiently long so that when they are held approximately in ahorizontal position as by means of a bolt 74 as shown in Figs. 1 and 5the center line between pivot pin 79 and bracket 56 falls to the rightof bearing 43. As a result of this construction all that it is necessaryto do to condition the apparatus for automatic operation is to insert abolt 74 through an aperture 72 provided for this purpose in each offlanges 46, each bolt being preferably retained in place with aretaining nut 76. In order to condition the apparatus for non-automaticoperation, all that the user has to do is remove the bolt 74.

The operation probably will be apparent from the foregoing descriptiontogether with the following explanation. During the opening movement ofthe door, of course, the upper end of the door is guided rearwardly bythe tracks 22 while the lower end is swung arcuately upwardly by thepivoting of the arms 32 about the bearings 43. The door iscounterbalanced by the tension of springs 54 acting on the free ends ofthe arms 32.

When the bolts 74 are inserted through the apertures '72 to hold thelinks 66 in the generally horizontal position depicted in Fig. 1, itwill be recognized that the springs 54 produce an initial moment armaction about the pivot 68 to urge the lower end of the door outwardly.In this way, when the door is unlatched, the spring 54 will causeimmediate movement of the swinging arms 32 about the pivot point 48,thus opening the door. However, when the bolts 74 are removed from theapertures 72, then the links 66 assume a somewhat vertical position asseen in Fig. 3. This resulting relationship of links 66 reverses themoment arm inasmuch as the springs 54 act in a direction on the oppositeside of the pivot point 48 from that which they act in Fig. 1.Accordingly, in this latter situation, there is no tendency for thebottom of the door 16 to swing outwardly, and consequently in order forthe door to be opened after unlatching it, a manual force must be firstapplied in order to move the lower end of the door outwardly. When thedoor has been moved manually far enough to bring the center line betweenpivot pin 68 and bracket 56 to the right of bearing 48, the springs 54then become effective to raise the door into the horizontal position itassumes when the door is fully opened.

It will be apparent that when the door is fully opened, the arms 32 willhave pivoted through an angle of approximately 180 degrees from theposition shown in Figs. 1 and 3 and the end of the arms connected to thebracket 34 will then be uppermost. In this position, the links 66 willno longer engage the bolts 74 if such bolts are present 4t and willclear the apertures 72. Thus when the door is opened it is a simplematter to insert or remove the bolts 74 to obtain whatever type ofaction is desired. It thus will be seen that automatic or non-automaticoperation is attained with a single simple mechanism and adjustment maybe easily and quickly accomplished.

As many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the followingclaim is intended to cover all of the generic and specific features ofthe invention herein described and all statements of the scope of theinvention which, as a matter of language, might be said to falltherebetween.

I claim:

A counterbalance for a door movable from a vertical position in a doorframe when closed to an overhead horizontal position when opencomprising a swingable arm, a first pivot adapted to be fixed to thedoor frame and connected to said arm intermediate the ends of the arm,means for pivotally securing one end of the arm to the door adjacent the1 wer edge of the door, a tension spring, means for anchoring one end ofthe spring adjacent the bottom of the door frame, a link pivotallyconnected at one end to the other end of the spring, a second pivotconnecting the link to the free end of the swingable arm for movementbetween a first position wherein the line of force of said spring is onthe opposite side of said first pivot from the door and a secondposition wherein the line of force of said spring is between the doorand said first pivot when the door is closed, and a removable boltsecured to the free end of the swingable arm for engagement with thefree end of the link to hold the link in said first position.

References Cited in the file of this patent UNITED STATES PATENTS2,516,196 Fowler July 25, 1950 2,544,952 Deuring Mar. 13, 1951 2,549,140Svendsen Apr. 17, 1951

